Coastal vegetated ecosystems constitute very productive habitats, characterized by efficient C sequestration and long-term preservation in sediments, so they play an important role in climate change mitigation. The temporal evolution of C content, stocks and burial rates were evaluated in seagrass and salt marsh habitats in San Quintin Bay (northeast Pacific, Mexico) by using Pb-dated sediment cores. Salt marsh cores were characterized by fine-grained sediments, higher salinities, lower terrigenous input and lower mass accumulation rates (MAR: 0.01-0.03 g cm yr) than seagrass cores (MAR: 0.02-3.21 g cm yr). Accumulation rates in both habitats steadily increased throughout the past century most likely because of soil erosion promoted by land use changes in the surroundings. The C stocks were highest in salt marsh cores (12.2-53.6 Mg ha at 10 cm depth; 259-320 Mg ha at 1 m depth) than in seagrass cores (5.7-14.4 Mg ha, and 80-98, Mg ha, respectively), whereas C burial rates were considerably lower in salt marsh (13-60 g m yr) than in seagrass (9-144 g m yr) habitats, and the temporal variations observed in C burial rates were mostly driven by changes in the accumulation rates. The overall C stock (485 ± 51 Gg C) for both habitats together was comparable to the carbon emissions of a major city nearby. Our results highlight the need to protect these environments as relevant carbon reservoirs.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1016/j.scitotenv.2019.03.388 | DOI Listing |
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!